Efficient heat storage and release device and optimization design method thereof

Abstract

The invention discloses an efficient heat storage and release device and an optimization design method thereof.The heat storage and release device comprises an outer shell and an inner shell, the space between the outer shell and the inner shell is filled with a heat preservation material, the inner side of the inner shell is filled with a phase change heat storage material, and a heat storage heat transfer pipe and a heat release heat transfer pipe are embedded in the phase change heat storage material; and the heat storage and heat transfer pipe and the heat release and heat transfer pipe are arranged along the opposite sides of the inner shell, transversely penetrate through the inner shell, the thermal insulation material and the outer shell and extend outwards. According to the efficient heat storage and release device, no melting dead zone exists in the heat storage and release process, the effective heat storage capacity is large, the heat exchange enhancement effect is achieved under the natural convection effect, meanwhile, the heat transfer temperature difference between the heat storage and release heat transfer pipe and the phase change material is large, and the heat storage and release process is always kept in an efficient state.

Description

Technical Field

[0001] The invention belongs to the field of energy technology, and in particular relates to a high-efficiency heat storage and release device and an optimization design method thereof. Background Art

[0002] The imminent energy shortage and high energy costs have always been the focus of scientific attention. In many systems, the mismatch between energy supply and demand in time and intensity has caused a lot of energy waste. Phase change heat storage technology is an effective means to solve this problem, but there are mainly the following problems in the operation of heat storage and release devices: ① The thermal conductivity of phase change materials is low and the heat transfer speed is slow; ② The heat transfer temperature difference between the heat transfer tube and the heat storage material is reduced, and the heat flux density of the heat transfer tube is reduced; ③ There is a "dead zone" that is difficult to melt, which reduces the effective heat storage capacity of the heat storage and release device. The heat storage and release rate is closely related to the flow heat transfer characteristics of the phase change material, and the flow heat transfer characteristics of the phase change material mainly depend on the shape and structure of the heat storage and release device. This requires that the structural form of the heat storage and release device be reasonably designed according to the principles of fluid mechanics, while taking into account the optimization of the heat transfer performance of the heat storage and release process. At present, satisfactory results have not been achieved for the flow heat transfer characteristics of phase change materials and the optimization design of heat storage and release devices, which seriously restricts the application of heat storage and release devices in production and life. Summary of the invention

[0003] In order to solve the above technical problems, the present invention proposes a high-efficiency heat storage and release device and an optimization design method thereof. The heat storage and release device has the advantages of simple structure, convenient processing and manufacturing, low cost, large effective heat storage capacity, high heat storage and release efficiency, and the ability to store and release heat simultaneously. The optimization design method can be used to design a matching heat storage and release device according to the specific needs of the user to meet the needs of different users.

[0004] The present invention provides a high-efficiency heat storage and release device, comprising: an outer shell and an inner shell, wherein a heat insulation material is filled between the outer shell and the inner shell, and a phase-change heat storage material is filled inside the inner shell, and a heat storage heat transfer pipe and a heat release heat transfer pipe are buried inside the phase-change heat storage material, and the heat storage heat transfer pipe and the heat release heat transfer pipe are arranged along opposite sides of the inner shell, and the heat storage heat transfer pipe and the heat release heat transfer pipe extend outward across the inner shell, the heat insulation material and the outer shell.

[0005] Optionally, the outer shell is a rectangular parallelepiped, and the inner shell is a column.

[0006] Optionally, the heat storage heat transfer tube and the heat release heat transfer tube are both composed of a group of heat transfer tubes arranged in parallel.

[0007] Optionally, the distance d between the heat storage heat transfer tube and the heat release heat transfer tube is: 10d≤D≤20d, wherein D is the length of the outer shell.

[0008] The present invention also provides an optimization design method for a high-efficiency heat storage and release device, comprising:

[0009] Get user-side variables;

[0010] According to the user-side variables, obtaining the size of the heat storage inner shell of the heat storage and release device;

[0011] The heat storage time is obtained according to the size of the heat storage inner shell.

[0012] Optionally, the user-side variables include: the thermal fluid temperature of the heat storage and release device, the effective heat storage capacity of the heat storage and release device, the type of phase change material, the phase change temperature of the heat storage material, the density of the heat storage material, the phase change latent heat of the heat storage material, the thermal diffusion coefficient of the phase change material and the specific heat capacity of the phase change material.

[0013] Optionally, the method for obtaining the heat storage time is:

[0014]

[0015] Among them, t is the heat storage time, H is the height of the heat storage inner shell, d is the distance between the heat storage heat transfer tubes, R l is the radius of the heat storage heat transfer tube, L is the latent heat of phase change of the heat storage material, a is the thermal diffusion coefficient of the phase change material, c is the specific heat capacity of the phase change material, T1 is the temperature of the hot fluid, T x is the solidus temperature of the thermal storage material.

[0016] Compared with the prior art, the present invention has the following advantages and technical effects:

[0017] 1. The high-efficiency heat storage and release device of the present invention has the advantages of simple structure, convenient processing and manufacturing, low cost, and the ability to store and release heat simultaneously.

[0018] 2. The high-efficiency heat storage and release device of the present invention does not have a melting "dead zone" during the heat storage and release process, has a large effective heat storage capacity, and under the action of natural convection, it plays a role in enhancing heat exchange. At the same time, the heat transfer temperature difference between the heat storage and release heat transfer pipe and the phase change material is large, and the heat storage and release process is always maintained in a high-efficiency state.

[0019] 3. The optimization design method of the present invention has a wide range of applications. Suitable phase change materials can be selected according to user requirements, and matching heat storage and release devices can be designed to meet the needs of different users. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0021] Figure 1 This is a structural diagram of a high-efficiency heat storage and release device according to an embodiment of the present invention;

[0022] Figure 2 It is a principle diagram of the heat storage and release process of an embodiment of the present invention. DETAILED DESCRIPTION

[0023] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0024] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0025] The working principle of the present invention is:

[0026] like Figure 2 As shown, during the heat storage process, the heat storage heat transfer tube at the bottom melts the surrounding phase change material, and the phase change material moves upward under the action of natural convection and melts the phase change material above, so that there is no melting "dead zone" in the entire heat storage cavity; under the action of natural convection, the high-temperature phase change material has a lower density and moves upward, and the low-temperature phase change material has a higher density and moves downward, so that a large heat transfer temperature difference is always maintained around the heat storage heat transfer tube, which is in a highly efficient heat storage state.

[0027] like Figure 2 As shown, during the heat release process, the heat transfer tube above absorbs the heat of the surrounding phase change material. Under the action of natural convection, the low-temperature phase change material with higher density moves downward, while the high-temperature phase change material with lower density moves upward, so that a large heat transfer temperature difference is always maintained around the heat transfer tube, which is in a highly efficient heat release state.

[0028] The present invention provides a highly efficient heat storage and release device, such as Figure 1 As shown, the specific structure includes: an outer shell and an inner shell, the outer shell and the inner shell are filled with heat insulation material, the inner side of the inner shell is filled with phase change heat storage material, heat storage heat transfer pipes and heat release heat transfer pipes are buried inside the phase change heat storage material, and the heat storage heat transfer pipes and heat release heat transfer pipes are arranged along opposite sides of the inner shell, and the heat storage heat transfer pipes and heat release heat transfer pipes extend outward across the inner shell, the heat insulation material and the outer shell.

[0029] Specifically, the high-efficiency heat storage and release device has a rectangular shape, with a heat storage inner shell wrapping a phase change heat storage material, and a thermal insulation material is filled between the outer shell and the heat storage inner shell. The heat storage heat transfer tube and the heat release heat transfer tube are composed of multiple groups of parallel tubes. The heat storage heat transfer tube and the heat release heat transfer tube are respectively arranged at the lower part and the upper part of the heat storage and release device, and cross the heat storage inner shell and the phase change heat storage material. The heat storage heat transfer tube flows a hot fluid, and the heat release heat transfer tube flows a cold fluid.

[0030] Furthermore, the outer shell is a rectangular parallelepiped, and the inner shell is a column.

[0031] Specifically, the high-efficiency heat storage and release device has a rectangular shape with a length of D, a width of D, and a height of 2D. The heat storage inner cavity is cylindrical. This structure enables the heat storage material to always maintain a high natural convection intensity during the heat storage and release process, which helps to enhance heat transfer.

[0032] Furthermore, the heat storage heat transfer tube and the heat release heat transfer tube are both composed of a group of heat transfer tubes arranged in parallel.

[0033] Specifically, the heat storage heat transfer tubes and the heat release heat transfer tubes are composed of multiple groups of parallel tubes. The heat storage heat transfer tubes are arranged at the lower part of the heat storage and release device, and the heat release heat transfer tubes are arranged at the upper part of the heat storage and release device, so as to maximize the natural convection movement of the heat storage material for heat transfer, always keep the heat transfer temperature difference between the heat storage heat transfer tubes and the heat release heat transfer tubes to be maximized, and realize the efficient operation of the heat storage and release process; the heat storage heat transfer tubes are arranged at the lower part of the heat storage and release device, and the heat release heat transfer tubes are arranged at the upper part of the heat storage and release device. Due to the effect of natural convection, the heat storage and release device with this structure is not easy to produce a "melting dead zone" during the heat storage and release process, so as to maximize the effective heat storage volume.

[0034] Furthermore, the distance d between the heat storage heat transfer tube and the heat release heat transfer tube is: 10d≤D≤20d, wherein D is the length of the outer shell.

[0035] Specifically, the distance d between the heat storage heat transfer tube and the heat release heat transfer tube of the high-efficiency heat storage and release device has the following relationship: 10d≤D≤20d, so as to prevent the "melting dead zone" from occurring during the heat storage and release process due to excessive distance.

[0036] The present invention also provides an optimization design method for a high-efficiency heat storage and release device, comprising:

[0037] Get user-side variables;

[0038] According to the user-side variables, the size of the heat storage inner shell of the heat storage and release device is obtained;

[0039] The heat storage time is obtained according to the size of the heat storage inner shell.

[0040] Specifically, the method has a wide range of applications, and suitable phase change materials can be selected according to user-side requirements.

[0041] Furthermore, the user-side variables include: the temperature of the thermal fluid of the heat storage and release device, the effective heat storage capacity of the heat storage and release device, the type of phase change material, the phase change temperature of the heat storage material, the density of the heat storage material, the latent heat of the phase change of the heat storage material, the thermal diffusion coefficient of the phase change material and the specific heat capacity of the phase change material.

[0042] Specifically, the size of the heat storage inner shell of the heat storage and release device is calculated according to the user-side variables.

[0043] The volume of the heat storage cavity (phase change material) is:

[0044] The length and width of the heat storage inner shell are:

[0045] The height of the heat storage inner shell is:

[0046] Among them, the heat storage material density ρ, the heat storage material phase change latent heat L and the effective heat storage capacity Q.

[0047] Furthermore, the method for obtaining the heat storage time is:

[0048]

[0049] Among them, t is the heat storage time, H is the height of the heat storage inner shell, d is the distance between the heat storage heat transfer tubes, R l is the radius of the heat storage heat transfer tube, L is the latent heat of phase change of the heat storage material, a is the thermal diffusion coefficient of the phase change material, c is the specific heat capacity of the phase change material, T1 is the temperature of the hot fluid, T x is the solidus temperature of the thermal storage material.

[0050] Specifically, the simplified calculation method for heat storage time is (applicable to situations where accuracy is not required):

[0051]

[0052] Among them, the total surface area of ​​multiple groups of heat storage and heat transfer tubes is F, the temperature of the hot fluid is T1, and the phase change temperature of the heat storage material is T x The convection heat transfer coefficient of the heat storage tube surface is h. For general phase change materials, it can be calculated as 200W·m -2 / K value.

[0053] The solar water heating system in a factory dormitory building is used as an example to explain in detail:

[0054] It is planned to set up an efficient heat storage and release device to meet the hot water supply on cloudy days. Water is used as the circulating working fluid. Under the heat storage condition, the water temperature is 80℃, the effective heat storage capacity is 630000kJ, and the heat storage material is paraffin. The phase change temperature is 60℃, the phase change latent heat is 200kJ / kg, the density is 900kg / m3, the specific heat capacity is 1500kJ / kg·K, and the thermal conductivity is 0.2W / m·K.

[0055] The volume of the heat storage cavity (phase change material) is:

[0056] The length and width of the heat storage inner shell are: The height of the heat storage inner shell is:

[0057] There are 15 heat storage and heat transfer tubes, the diameter of the heat transfer tube is 0.01m, and the tube spacing is 0.101m.

[0058] The heat storage time is calculated according to the precise algorithm:

[0059]

[0060] The use of the high-efficiency heat storage and release device and the optimization design method thereof can effectively improve the effective heat storage capacity of the heat storage and release device, achieve efficient and stable heat storage and heat release, and reduce the heat storage time.

[0061] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A high-efficiency heat storage and release device, characterized in that: include: An outer shell and an inner shell, wherein a heat-insulating material is filled between the outer shell and the inner shell, and a phase-change heat storage material is filled inside the inner shell, and a heat-storage heat transfer tube and a heat-release heat transfer tube are buried inside the phase-change heat storage material, and the heat-storage heat transfer tube and the heat-release heat transfer tube are arranged along opposite sides of the inner shell, and the heat-storage heat transfer tube and the heat-release heat transfer tube cross the inner shell, the heat-insulating material and the outer shell and extend outward.

2. A high-efficiency heat storage and release device according to claim 1, characterized in that: The outer shell is a rectangular parallelepiped, and the inner shell is a column.

3. A high-efficiency heat storage and release device according to claim 2, characterized in that: The heat storage heat transfer tube and the heat release heat transfer tube are both composed of a group of heat transfer tubes arranged in parallel.

4. A high-efficiency heat storage and release device according to claim 2, characterized in that: The distance d between the heat storage heat transfer tube and the heat release heat transfer tube is: 10d≤D≤20d, wherein D is the length of the outer shell.

5. An optimization design method for a high-efficiency heat storage and release device, characterized in that: include: Get user-side variables; According to the user-side variables, obtaining the size of the heat storage inner shell of the heat storage and release device; The heat storage time is obtained according to the size of the heat storage inner shell.

6. The optimization design method of a high-efficiency heat storage and release device according to claim 5, characterized in that: The user-side variables include: the temperature of the thermal fluid in the heat storage and release device, the effective heat storage of the heat storage and release device, the type of phase change material, the phase change temperature of the heat storage material, the density of the heat storage material, the latent heat of the phase change of the heat storage material, the thermal diffusion coefficient of the phase change material and the specific heat capacity of the phase change material.

7. The optimization design method of a high-efficiency heat storage and release device according to claim 5, characterized in that: The method for obtaining the heat storage time is: Among them, t is the heat storage time, H is the height of the heat storage inner shell, d is the distance between the heat storage heat transfer tubes, R l is the radius of the heat storage heat transfer tube, L is the latent heat of phase change of the heat storage material, a is the thermal diffusion coefficient of the phase change material, c is the specific heat capacity of the phase change material, T1 is the temperature of the hot fluid, T x is the solidus temperature of the thermal storage material.

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